Zero-bias anomaly in self-organized nanostructures in the ternary system Au/Co/Ge(001)

The formation of a class of self-organized, one-dimensional nanostructures in the ternary material system Au/Co/Ge(001) is reported. These "nanorods" form after the subsequent deposition of Co and Au on the clean Ge(001) surface, followed by thermal annealing. The local structural and electronic properties were probed using scanning tunneling microscopy and spectroscopy. Various types of nanorods exist and their distribution and mean length are controlled by the amount of deposited Co and the annealing temperature. Differential tunneling conductance measurements indicate the existence of four dominant peaks near the Fermi energy and an anomalous suppression of the differential tunneling conductance at the Fermi level, resulting in a zero-bias anomaly.